The present invention relates to improvements in apparatus for reproduction of sound or other intelligence on selected portions of one or more magnetic tapes, wires or analogue carriers of information. More particularly, the invention relates to improvements in systems which can effect one or more reproductions of intelligence which is stored on selected segments or portions of disc-, web- or wire-like carriers (hereinafter referred to as magnetic tapes for short). Still more particularly, the invention relates to improvements in apparatus for reproduction of sound or other intelligence on selected portions of one or more magnetic tapes, as concerns the accuracy of the repetition cycle, i.e., the probability that the start and the end point of a carrier portion bearing intelligence to be reproduced several times will be located exactly over and over again independently of the number of repetitions.
It is already known to provide apparatus or attachments which can be combined with or incorporated in magnetic tape recorders and serve to allow for repeated reproduction of sound which is stored on magnetic tape. Certain presently known apparatus are not sufficiently sophisticated to allow for reproduction of sound on selected portions of magnetic tape, i.e., the sound which is recorded on the tape must be reproduced in its entirety. This is the case when the tape consists of an endless tape-loop. The length of the magnetic tape is then limited, i.e., a first tape-loop must be replaced with a second tape-loop which is longer than the removed one if the amount of sound to be recorded is such that it cannot be stored on the first tape-loop. Still further, presently known apparatus which are designed to allow for repeated reproduction of entire intelligence which is recorded on magnetic tape are not suited for a variety of purposes, for example, when a student desires to select the overall amount of intelligence which is to be stored on a tape as well as those portions of intelligence which are to be reproduced once or more than once.
U.S. Pat. No. 3,913,133 granted Oct. 14, 1975 to Aregger (corresponding to Swiss Pat. No. 549,256) discloses a method and apparatus which allow for repeated reproduction of sound on selected portions of magnetic tape. The patented apparatus employs two dynamically operated mechanical counters which respectively register the distances covered by the magnetic tape in first and second directions. When the registered distance in one direction has reached a preselected absolute value, detected by one counter, the movement of the tape is reversed and the second counter starts registering the distance covered by the carrier in the opposite direction, until the second counter registers again a preselected value according to the length of the sequence to be repeated. The direction of movement of the carrier is thereupon reversed and the first counter starts registering the distance in forward direction.
Thus, two dynamically operated mechanical counters for measurement of the length of the carrier portion during a repetition cycle interact with each other to define the reptition cycle. The use of these two counters which are operatively coupled to each other may adversely affect the accuracy of locating the end points of the repetitions cycle, especially when repeated several times.
British Pat. No. 912,462 granted to AKAI describes a method and apparatus which also allow for repeated reproduction of sound or intelligence. A dial is operatively coupled to the tape for movement during repetition. The dial performs a rotational movement as a result of conversion of the linear tape movement into a rotational movement. A rotably mounted knob on the dial is not coupled to the tape, i.e., it must be rotated by operator. A slip ring is mounted on and is in sliding contact with the dial so that it can be rotated relative to the dial by an operator and is additionally frictionally driven by the dial according to the tape movement. The dial carries a first contact cooperating with a second contact on the knob, and a third contact which is rigidly mounted on the frame of the apparatus cooperates with a projection on the slip ring. Engagement of first and second contacts defines one end of the repetition cycle, and engagement of the projection with the third contact defines the other end of the cycle. Basically the position of the tape is compared with a preselected position by interaction of dial contact and knob contact for a first end position. One dynamically operated means (dial contact) interacts with a settable stationary means (knob contact) the setting of which is analogous to the setting of a storing means to a fixed value which is to be compared with a dynamic value given by the position of dial contact varying in time with the tape movement. Setting of the slip ring on the dial the latter being dynamically operated and is analogous to establishment of a phase difference between two dynamical values. Dial contact and slip ring projection are both dynamically operated as a function of the tape movement. The fact that, for definition of the two end points of the repetition cycle, the slip ring has to be set on the movable dial entails serious disadvantages as concerns the construction as well as the accuracy of repeatedly locating the desired end points of the cycle to be repeated. As an example, interaction of projection on the slip ring with the rigidly mounted third contact may result in movement of the ring with respect to the dial and thus alter the length of the preselected cycle. This is likely to occur after the reset of the slip ring on the dial has been worn out by use.
A drawback of the just described apparatus is that it is incapable of insuring repeated reproduction of sound on one and the same segment of magnetic tape. This is due to the fact that the known apparatus employ a larger number of dynamically operated parts than absolutely necessary to locate the two end points of the repetition cycle. Other related prior art which was considered by and/or is known to applicants includes U.S. Pat. Nos. 3,571,524, 3,681,523, 3,921,215, 3,812,532, 3,949,420, 3,913,133, British Pat. Nos. 1,313,226, 1,195,775, 969,640, 931,809, 743,448, 912,462, German laid open print No. 2 425 856 and Swiss Pat. No. 520 384.